Species validation and cryptic diversity in the Geophagus brasiliensis Quoy & Gaimard, 1824 complex (Teleostei, Cichlidae) from Brazilian coastal basins as revealed by DNA analyses

Many allopatric populations of the pearl cichlid Geophagus brasiliensis show remarkable morphological, chromosomal, and DNA sequence divergence. As a result, Geophagus brasiliensis is regarded as a species complex, combining recent descriptions of new species and several uncertainties about their actual richness. In the present work, we evaluated the number of evolutionary units in this fish complex along hydrographic basins in northeastern Brazil by using the DNA barcode, species delimitation algorithms and phylogenetic analyses. A total of 14 molecular operational taxonomic units (MOTUS) were identified with high support values and mean differentiation within and among groups of 0.4 and 12.7%, respectively. The DNA sequences supported Geophagus itapicuruensis as a valid taxon, besides indicating likely undescribed species. Moreover, the evolutionary units in coastal basins of useful to infer the evolutionary units in a cryptic and widespread fish group from the Neotropical region. Finally, the undescribed taxa in coastal basins of northeastern Brazil were clearly differentiated from Geophagus brasiliensis sensu stricto. The present data highlight the importance of conserving regional ichthyofauna since unique evolutionary lineages are potentially threatened by environmental degradation, invasive species and construction of dams.